One of the consequences of the strong influence of applied psychology on human ability research is that a schism has developed between the psychometrician and the experimental psychologist. Thus, although the study of human cognition is currently more intense than at any previous time, most current theories of cognition do not deal in any detail with the individual differences. The purpose of the proposed research is to begin to lay the groundwork for a rapprochement between psychometrics and the experimental study of cognition. A series of experiments designed to reveal the relationships between the traditionally-measured traits of verbal, motor, and quantitative ability on the one hand, and the parameters of typical information-processing models of cognition on the other are proposed. By examining a variety of intellectual tasks, it should be possible to find those parameters that are most crucial in determining different types of intellectual performance. Tests may then be derived to measure those parameters directly. Collectively, these traits would constitute a theoretically-based measure of intelligence. Moreover, such a measure would be diagnostic rather than merely descriptive since it would more precisely define what aspects of intelligence are potentially modifiable and how such modifications may be obtained.